Ketamine users particularly prone to bizarre physical experiences
A popular “club drug” promises to open a scientific window on the strange world of out-of-body experiences, researchers say.
Recreational users of a substance called ketamine often report having felt like they left their bodies or underwent other bizarre physical transformations, according to an online survey conducted by psychologist Todd Girard of Ryerson University in Toronto and his colleagues.
Ketamine, an anesthetic known to interfere with memory and cause feelings of detachment from one’s self or body, reduces transmission of the brain chemical glutamate through a particular class of molecular gateways. Glutamate generally jacks up brain activity. Ketamine stimulates sensations of illusory movement or leaving one’s body by cutting glutamate’s ability to energize certain brain areas, the researchers propose in a paper published online February 15 in Consciousness and Cognition.
“Ketamine may disrupt patterns of brain activation that coalesce to represent an integrated body and self, leading to out-of-body experiences,” Girard says.
National surveys indicate that 1.6 percent of high school seniors in Canada and the United States have used ketamine at least once. An estimated 70 percent of Toronto rave-goers now report taking ketamine at these all-night parties, Girard notes.
In the new survey, use of marijuana, LSD and MDMA, also known as ecstasy, displayed modest links to volunteers’ reports of illusions of walking or moving rapidly up and down while actually remaining still. But only ketamine use exhibited a strong relationship with having had a range of out-of-body experiences, regardless of any other drugs ingested at the time of those sensations, researchers say.
Neuroscientist Olaf Blanke of the Swiss Federal Institute of Technology in Lausanne calls ketamine “an interesting candidate to further understand some of the brain mechanisms in out-of-body experiences.” Blanke, who like a growing number of scientists studies these phenomena in controlled experiments (SN: 6/5/10, p. 10), says that drugs such as ecstasy and amphetamines also deserve close scrutiny.
Blanke has linked out-of-body experiences to reduced activity in brain areas that integrate diverse sensations into a unified perception of one’s body and self. Ketamine and other recreational drugs act throughout the brain, making it difficult to explain how any one drug might specifically affect sensation-integrating tissue, Blanke says.
Girard’s team administered online surveys about drug use and drug-related experiences to 192 volunteers, ages 14 to 48. Almost half the sample reported having used marijuana, alcohol, ecstasy, ketamine and amphetamines. Roughly two-thirds had taken ketamine, and nearly everyone had used marijuana and alcohol.
Almost three-quarters of all participants reported having had a feeling of temporarily leaving their bodies, usually on several occasions. About 42 percent had experienced seeing their own bodies from an outside vantage point. Feelings of rapidly moving up and down, falling, flying or spinning had affected more than 60 percent of volunteers. Another 41 percent reported illusions of sitting up, moving a limb or walking around a room, only to realize that they had not moved.
Of those reporting feelings of leaving their bodies, 58 percent were under the influence of ketamine at the time. Ketamine use also displayed a close association with other unusual bodily sensations.
Apparent effects of drugs such as ecstasy on out-of-body experiences were largely explained by associated ketamine use, Girard says.
By Bruce Bower
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